Automatic steering for dirigible craft



Dec. 18, 1928.

c. a. MILLS 1,595,601

AUTOMATIC STEERING FOR DIRIGIBLE CRAFT Filed June 19. 1922 5 Sheets-Sheet l Dec. 18, 1928. Y 1,695,601 c. B. MILLS 'AUTOMATIC STEERING FOR DIRIGIBLE CRAFT Filed June 19. i922 5 sheets-sheet '2 3512* www Dec. 18, 1928. 1,695,601

- f c. B. MILLS AUTOMATIC STEERING FOR IRIGIBLE lCRAFTv Filed June 19. 1922 5 sheets-sheet 5 Dec. 18, 1928. 1,695,601'

c. B. MILLS AUTOMATIC STEERING FOR DIRIGIBLE CRAFT Filed June 19, 1922 5 sheets-sheet 4 dif/.7W f

Dec.

C. B. MILLS Filed Jun 19. 1922 AUTOMATIC STEERINGv FOR DIRIGIBLE CRAFT -5 Sheets-Sheet 5 Patented Dec.M4 18, 1928.

UNITED STATES .PATENT y OFFICE..

`CHESTER B. MILLS, or BROOKLYN, NEwYoR-mAssIGNoR'To THESPERRY GYRos'corE COltlPAlSFY, OF* BROOKLYN, NEW YORK, A CORPORATION OF NEWT YORK.

AUTOMATIC STEERING DIRIGIBLE CRAFT.

A ppneauon' ined Jungle,

l, This invention relatesA to thenavigation of all kinds of craft, more-especially to the steering of'` dirigible craft such fas vessels,

`and aircraft which are guided by means of a rudder. In the automatic steering' of dirigiblecraft, especially" where the rudder and the 4driving power are both located at thestern of the craft, as in'ships, thereis a. tendency to throw the craft into unstable equilibrium `/so .far as direction 1s .conce rned. 'This 1s indi- 1922. Serial No. 569,295.

alarm or signal to give a 'suitable lindication Other objects and advantages will in part be obvious and in part specifically pointed out in the specification.

' In the accompanying drawings,

Fig. 1 .is a front elevation of that portion of the steering apparatus which .is adapted to be placed in thepilot house of a vessel,

y cated by the constant 'tendency'of suclrcraft and showing a preferred form of my uvam to deviate from the true course, an act known-\ tlolrapplled thereto.

1 tendency to a degree which may be known asv anticipation. lOne form vof apparatus for accomplishing this function is disclosed "in the patent to Elmer A. Sperry, No. 1,360,694

dated November 30, 1920, onwhich this invention is an improvement. After f pro-y tracted investigation, including sea trials which have been followed to the extent of tinally successfully steering very large ships, meanshave been developed, as herein disclosed to accomplish these functions which are simple, inexpensive and operate with less lag c ne of the objects ofthe invention andan improvement effected by it is the preventingl ofthe ship when swingingbackto her course, fro In ina itime parlance, this is termed meeting the ship. To accomplish this automati cally, means are provided to retard the `angular movement `of the ship, especially as it 'approaches such heading. "By vthismeans 'f the yaw is damped out eectively.-

It is a further object of this invention to` provide means whereby a new course may be set and means Jfor automatically directing the vessel rapidly into said course) A furtherl ob'ect is the' provisionof'means for automatically. setting the rudder, when itl is desired to swing the vessel through a desired angular distance, toa degree propor-l tional to saidangular distance;

. A further Objectis th provision of an automatic steering device which may be controlledy from a master gyroscopic compass, but so constructed as to prevent transmission of the hunt of said compass to the steering device. K

A further object is the provision of an swinging beyond the proper heading.

'F1g. 2 is a vertical. section through the master controller shown inv Fig. 1. Fig. 2A is a detail of a portion ofthe mechanlsm for preventing transmission of the hunt of the compass. j Fig. v8 is a fronttelevatior similar to Fig.. l lbut employing another form of master con? troller. 4

ig. 4 is a, plan vi'ewof the controller shown in Fig. Fig. 5 is a vertical section of the master controller shpwn in Fig. 3. i

Fig. 6 vis al plan view ofv shown in' Figs. 1 and' 2. Fig. 7 is alpla-n View of the auxfiliaryconthe controller trol `device which operates inconjunction 'with 'the master controller and may form a part thereof.

Fig.' 8 is a front elevation of the device shown in Fig. 7.

Fig. 9 is a vertical section through the relay portion of the device shown in Fig. 7.

Fig. 10 isa wiring diagram of'one form of course control device.

Fig. 11 is a wiring diagram of a -sec'on'd form of course control device. F1g..'12 1s an orlgmal record of a ships `course, showing the results 'of automatic steering on the course of a' vessel.

Referring to Figs. 1 and Qnf the drawings,l for governing the course cfa ship', I locate, preferablyin the'pilot house 'of the ship, a master controller 1 from which the -rudder is .automatically eontrolled.- Said controller may assume a variety of forms. In Fig. l1 it is shown as mounted on a bracket 2 secured to the usual manner, vand the magnetic compass so I les

housing 6. In 3v a different form of master controller 1 is shown mounted on a stand 3 and which performs both the funcl' tion of a steering'repeater compass and a trolled from any form of azimuth indicator, y

preferably from a gyroscopic compass (not shown). Said motor is connected to a meins ber 15 which' may carry a pointer 16 or other course indicator, cooperating with a scale 17 on a settable annulus 5,5. The compass will thus maintain Apointer 16 fixed relatively tog :the'scale, if the gearing employed between motor 13 and the pointer is of the same ratio as that between the master compass and its transmitter. In practice, however, I prefer to employ less reduction gearing between the repeater motor 13 and the member 15 so that any deviation of the ship from its course is magnified. As shown, the shaft 20 of the motor 13 is provided with a pinion 21 meshing with a gear 22 which drives, in turn, pini'on 35. Said pinion 35 meshesjvithgear 36 which is shown as carrying member 15. To prevent the ,huntingaction ofthegyro compass from affecting member ,15, I prefer to provide a lost motion connection between gears 22 and 35. Gear 22 is secured to a bushing 23 journaled in a boss30 carried by an arin 31 fixed to the motor frame. A shaft 24 extends through said bushing and carries a cross-bar 25 at its upper end extending between prongs 26 on the upper end of bushing 23 and between the Wedge shaped ,slotss27 formed in a member 28 also journaled in boss 30 and having a gear 35 fixed thereto and meshing with a gear 36 to which member l5 is secured. It willthus be apparent that the hunt is transmitted by shaft 20 and gears 21 y and 22, bushing 23 and its prongs 26 -to the cross piece 25 enclosed between said prongs. The cross piece, however, has considerable lost motion in the wedge shaped slots 27 before it Vengages member 28 to" rotate gears 35 and 36,

and member 15'. This lost motion is sufficient to take up thefhunt and prevent its transmission to the member 15.

VBy moving cross-piece 25 upwardlyl to-l.. ward the apex of the wedge-shaped slot, it is apparent that there will be less free motion before said cross piece engages member 28,

vwhile by moving said cross piece downwardly toward the divergent end of the slot, the lost motion will be increased. The amount oflost .motion may -be regulated byproviding for I ablecain member /37 having a cam face 38 with, which engages an adjusting screw 39 threaded through casing 10 and operable Afiom outside thereof by a nut 4() fixed to va l shaft 41 carrying a forked member 42.be tween the ,prongs of which engages a pin 43 fixed to the screw 39. By rotating nut 40 to rotate screw 39 inwardly or outwardly, cam

Amember 37 is raised or lowered to raise or lower shaft 24 and cross piece 25. A spring 44 tends to return the shaft 24 and cross piece 25 to lowered position.

Although the oscillatory movements of the hunt arenotptransmitted to the member 15,

any deviation of' the ship from its course will cause relative displacement of pointer 16 and scale 17. At the same time there is brought into action mechanism which operates the rudder in such a manner as to bring the ship back to itsioriginal course. One form of mechanism is 'as` follows: In addition4 to pointer 16 there is fixed upon member 15 a circuit closing device comprising a pair of trolleys 50 contacting with split contact rings 51, 52, 53 (see Fig. 10) separated from each other by insulation 54.- Said contact rings are carried by a'rohtatablering 55 having a rack 56 fixed 'thereto so that it may be rotiited from outside the casing by a handle 60 operating a pinion 61 which meshes with said rack. The ring is set to'cause the shipto head in any l,desireddirection by reference to the repeater compass 4 (Fig. 1). When the ship is on its course, contacts 5,0 normally engage `the insulation 54, but as soon `as the ship deviates, arelative movement of trolley 50 and fring 55 occurs so that contacts 50 engage eon- '100 tact51 or 52, depending upon the direction of -deviation, to energizefield coil 62 or oppositely wound field coil 63, respectively, of a` steering enginecontrolling'motor'65, to drive rudder 66 in the direction which will tendto bring the ship back to its course. Said motor may either drive the rudder directly or through lthe ships telemotor agnd steering en.

gine system (hereinafter described) and may be located either forward adjacent the pilot wheel and controller or aft -adjacent the rudder. A f

Referring to Fig. 1, it will be observed that the repeater compass 4 is contained in a separate casing from casing 10 containing the master controller which inthis instance is provided with an arbitrary scale 17. The

steering compass and master controller may, y if desired, be mounted 1n the same casing, as

shown in Figs. 3 to 5, in which case the stand-` ard repeater card 252 cooperates with the settable course indicator 250. For this purpose pointer 250 is mounted upon a shaft 251 con centric with compass card 252 controlled froma repeater motor 13. The entire mech. anism is-encloscd in a casing 2,55 having thev usual glass cover 256 and bezel 257. The compass card is rotated by the compass repeater motor 13 through gears 258, 259 to-rotate shaft 260 and gear '261 thereon, gear 261 meshing with gear 262 on a bushing 263 jourllos naled in a partition plate 264, said compass card being fixed to the upper end of said bushing.

To set the pointer relative to the compass card, the usual handle 6U may be provided which operates by means of bevel gear 61, a differential comprising upper gear 265 and lower gears 266, 267, the gears 265 and 267 meshing with gears 27() and 271 of a. planetary member 269 fixed to shaft 260. Since' shaft 260 is rotated by the repeater motor, operation of handle will rotate gears'270 and 271 abouttheir axes to rotate gear 265 and gear 273 fixed thereto,said gear 273 meshing with gear 274 fixed to the pointer shaft 251. Fixed to gear 265 isa trolley 50 meshing Iwith contact strip 51 arranged in the form of rings, as in the Fig. 2 deviee'hereinbefore i fdescribed, except that said rings are here shown positioned to one side of the casing. It will be obvious that when a new course is set by .handle 60, trolley 50'will be moved along the contact strip, and that when the ship turns to move the contact strips relative to the trolley, the same circuits will be estab-- lished, as have beendescribed hereinbeforeA to move the ship to a new course or to bring it back after it has moved off its course.

In both the modifications shown in Fig. 1 and Fig. 3, the rudder may be operated either from themotor as described through shaft 65', or by the usual lsteering wheel 280 operated by hand. The latter'may be found desirable at times, as when entering or leaving port. For this purpose, a clutch 281 may be provided for throwing in or out the motorv drive which may operate through a link 65 connecting the motor and the rudder operating means. It will of course be understood that both the pilot whe-el 280 and motor 65 may operate the rudder through any desired form of steering engine on steamers of sufficient size to employ steering engines.

It should also be noted that in the form of master control shown in Fig. 3 and inthe auxiliary control device'70 as illustrated in Figs. 7 to 9, the contacts are rotated through a greater angle than the angle through which the compass apparently turns, thus in referring to Fig. 5,. it may be assumed that the repeater card 252 is rotated through the saine 'angle that the compass rotates through. This being the case, it will be readily apparent that the trolleys 50 are rotated through a much greater angle, since they rotate directly with l the gear 265 and pinion 273, while the compass card only rotates through, say one-tenth of that angle, due to the relative size of the pinion 273 and the gear 274. Also in Figs.P 7 and 9, the contractor is shown as rotated from the repeater motor, with only a one step reduction. Since it is common practice in the Sperry gyroscopic compass for the repeat-er motor to rotate one hundred and eighty times for one revolution of the compass, it will be readily seen that the commutator may be turnedthrough a much larger angle than `the compass. In fact, I prefer to turn the commutator through a larger angle than the trolleys 50, so as to make it more quickly responsive. to slight changes in the heading of the ship, for the purposes which will readily be apparent from the foregoing description of the auxiliary control device as hereinafter set forth.

If the problem of automatic steering were solved by the mere provision of settable, compass governed contacts, the solution would be simple, but as above explained, a ship does notl stay on a course for any great length of time, but practically continually tends to yaw off its course, swinging first toene side and then the other of the proper heading.

As la means of reducin awinfr I have demovement, starts the rudder back before the ship has regained its course, and in many caics brings the rudder to a point beyond its central position before the ship regains its course. rIhe yaw to the opposite side of the course vis thus anticipated and prevented, for otherwise,.the ship would be carried beyond its true course in the other direction. For this purpose there is interposed in the circuit between contacts 50, 5l, 52 and the oppositely wound-coils of the rudder control motor 65, or' otherwise introduced the auxiliary control device 7() (see Figs. 7,8 and 9), which is responsive to angular movement of the ship, whether that movement bc toward or away from its proper course.

Said device may be incorporated in the master controller itself, but I prefer to separately mount it, say, on a panel. It is mechanically operated from' a repeater motor 69 similar to motor 13 and also operatedffrom the master compass. The device comprises a set of brushes 71 and 72 normally in engagement with insulated contact sectors 73 of a commutator 75 connected to repeater motor 69, so as to be operated thereby only by changes in the direction of rotation thereof. Vhen the ship changes its course, therefore, the commutator is operated frolnthe repeater motor, so that brush 71 will engage a contact 76, or brush 72 will engage a Contact 77, depending upon the direction of' the yawing'movement or change in course,

so thatl a circuit will be established from troll ley 50 through contact 51, lead 79,' contact 76, brush 71, lead 80, to energize coll 81 to close the normally open relay 82 closing a circuit through lead 83, normally closed re-l the corresponding direction and so drive the rudder 66. l

If either of the above circuits is closed to operate the motor to drive the rudder in a given direction for eounteracting yawing of the ship, as soon as the ship begins to turn under the influence of the rudder, i. e.,

turn ina direct-ion opposite to the yawing movement, means are provided by this invention for reversing' the direction ofrotation of the rudder-,controlling motor and hence, returning the rudder to or near its initial position. Thereafter', the momentum of the ship will carryl it back to its course, whereas, if the rudder were not returned at the speciiiedtime, the momentumof the ship would carry it beyond its true course.

For the. purpose of illustrating the operation of the device. assume that. the ship has yawed so that trolley 50 has moved 5 along Contact 51. As the ship turns clockwise, the commutator turns counterclockwise rela tively thereto, because of its connection to the repeater motor 69, so that commutator 75 would ordinarily tend to travel say 100. with respect to the brushes, but stops 119, 120 on the commutator and fixed frame, respectively, are provided for limiting the relative movement of the commutator with respect to the ship to a small angle, and hence with respect to brushes 71 and '72. So that after a small movement of the commutator vrelative to the ship, the stops 119, 120 engage and the commutator is thereafter held stationary with respect to the ship, any further movementof the commutator relative to its shaft being taken up by a slip-friction connection shown in Fig. 9. The com mutator therefore, is immediately displaced with respect to the brushes upon a change in the angular movements or direction of yaw of the ship, whether that change be toward or away from the proper course.

Referring to said Fig. 9, a-shaft 95 is driven from the shaft 96 of the repeater motor through gears 97 and 98. In order to prevent transmission of the hunt of the compass to the commutator 75, there is provided a lost-motion connection between the shaft 95 and said commutator, in the form of a projecting finger, or bar 100, having frietional engagement with said shaft by means of friction discs 101 and 102 on shaft Disc 101 is provided with a hub 104 which is pinned toV shaft 95 byu pin 106fpassing through said hub and through au elongated slot (not shown) in the shaft 95 to permit longitudinal movement of said disc along said shaft. Disc 102 rests upon a shoulder form-cd on shaft 95, and disc 101 may be moved relative to disc 102 to vary the frictional Contact between the disc and bar 100. For this purposepa spring 107 at one end presses disc 101 towards disc 102 and at the other end engages a n ut 108 screw-threaded upon the end of shaft 95, so that by operating said. nut,l

spring 107 may be compressed to a greater or lesser degree to apply more or less friction be .Y

tweendiscs 101 and 102, and barlOO. Felt washers 105 Vare preferably. interposed between the bar and the discs. In this manner, y

the bar 100 is oscillated together with shaft 95 corresponding to the fhunt movements of the compass. Engagement kbetween the commutator and the bar 100 is effected through pins 109, 110, engaging in openings in the movements'. Any deviation in the course will cause movement of shaft 95 beyond the limits of the hunt to cause bar 100 to engage pin 109 or 110 to move the commutator in a di rcction opposite to the turning of the ship. The brush 71 or 72, therefore, slides along Contact 76 or 77 depending upon the direction of movement of the commutator. After a short distance, however, stops 119 and 120 engage to prevent further relative rotation of the commutator, and thereafter the comf mutator remains stationary in the extreme position until the ship starts turning in the other direction. When the stops 119 and 120 engage, the shaft 95 turns to overcome the fri'ctional engagement between discs 101 an d 102 and `bar 100, so that the latter is held stationary relative to the ship while the shaft continues to rotate. The commutator plate 111 is provided with a hub 112, said hub oper ating within a hub 113 fixed to the fixed frame and supporting said plate 111.

The brushes are pivoted as at 115 on a fixed plate 116 carried by frame 114, said brushes bein held in engagement with the commutator y springs 117. The movement of the commutator being thus narrowly limited, as soon as the ship starts back under the influence of the outwardly positioned rudl der, the motor 69 rotates the commutator to'` carrybrush 71 off contact 76 (in the example here discussed) to break the circuit through coil 63 while trolley 50 is still on contact 51.

The ship. however, continues to move in the return direction, commutator 75- carrying brush 72 into emgagementl with cont-act 77. No circuit is established through the reverse coil 62 to return the rudder, because contact 50 is still in engagement with contact 51 and hence has no connection to brush 7 2. There are therefore provided additional brushes 129 and 130 normally in engagement with insulating strips 131 on commutator 7 5. Thile brush 71 engages contact 76, brush 129 engages contact 132, and by main lead 140, lead 141, contact 132, brush 129, lead 133, and normally closed relay 134, continues along the ,same circuit, as that through contact 51 and brush 71 to relays 82 'closing a circuit leading through relay 84`to energize coil 63.

But as soon as brush 71 leaves contact 76 the circuit through relay 82 and hence through coil 63 `of the motorr is broken, and While trolley 50 is still in engagen'ientA with contact 51, further return movement of the ship causes further opposite rotation of the commutator and carries brush 130 into engagement' with contact 132. The brushes 129 and 130 are so positioned relative to contact l132 that only one of said brushes can contact therewith at any given time. A cir`- cuit is now established from` main lead 140 through lead 141, contac-t 132, brush 130, lead 142, normally closed relay 143, to energize coil 89 to close relay 90. A circuit is then established through relay 92 to the'coil 62 ofthe motor to reverse the direction of movement of the rudder. Further return movement of the ship causes the trolley 50 to be carried toward insulation 54, but this return movement is now due solely to the momentum of the ship, the rudder having been returned to substantially :central position. By this arrangement the return momentum of the ship is substantially damped out by I the time the ship reaches itscentral position.

When the rudder is returned, after the ship has started back, it is held in substantially central position by breaking the circuit established by brush 130 'through normally closed relay 143. This is accomplished by establishing a circuit from main lead 140, lead 145 to one end of the rudder, contact 146,

lead 152 through coil 147 of relay 143 to open said relay and break the circuit through coil .62 of` the motor. The circuit through motor 65 is completed by lead 148, rheostats 149, 15() to the other main lead 151, this portion of the circuit beingcontrolled by a relay 200, as will be more fully described hereinafter. 1f, however, the ship does not reach its proper course, the above cycle will be repeated until it does, as some yawing of the ship is always present to cause actuation of controller 70. If the shiphasnot suiiicient momentum to carry it back to its course it will turn oii again. Immediately trolley 50 Will engage contact I51 and brush 71 Will again engage contact 76 to energize field coil 63 of the motor. This actuates the rudder outwardly as before to give the ship a second return impulse. It will, of course, be appreciated that, the ship having been almost completely returned to its course by the rst impulse imparted to it by the rudder, the period ot actuation of the rudder before the ship again starts toward its course will bc very much less than the first time. The rudder will thus be actuated as often as is necessary `to return the ship to its course, ea-ch actuation being oi smaller duration than the preceding actuation because the deviation of the case Where the ship yaWs. clockwise so that trolley 50 engages contactf51,'brush'71 engages contact 76, and brush 129 engages contact 132. The circuits established where the ship yaws in the opposite direction Will be apparent and the operation is similar. It

may be described brieiiy as follows; trolley l50 engages Contact 52,'brush 72 engages Contact 77, and brush130 engages contact 132. The circuit lies through trolley 50, contact 52,

lead 87, contact 77, brush .72, lead 88, relay coil '89, closing Contact 9() and completing a circuit through lead 91, relay 92 tocoil 62 of the motor and from main lead 140,1ead y141, contact 132, brush 130, lead 142, relays 143 and 90, lead 9 1, relay 92, also to-coil 62. 85

This operates the rudder counter-clockwise to outward position. As soon as the shlp Starts in the return direction, the brush 72 Will move oif contact 77 and brush 130 will move off contact 132 to break the circuit through coil 90 i l 62 of the motor.' This is due to the slip friction connection, shown in Fig. 9, which lpermits only a slight movement of commutator 75 relative to its brushes, While trolley 50.

is f ree. to move through the entire angle of 95 deviation, so that brushes 72' and 130 move out'of engagement With contacts 77 and 132, .While trolley 50 is still in engagement with. Contact 52. Brush 129 noW moves into engagement With contactA 132 to establish a cir- 100 l cuit from mainlead 140, lead 141, contact 132, brush 130, lead 133, relays 134, relay coil 81 closing contact 82 and a circuit through lead 83 and contact 84 to opposite coil 63 of the motor. This returns the rudder, and

when the latter reaches a substantially central p osition, it engages contact 146 to establish a circuit from main lead 140, contact 146, lead 155, to energize coil 156 of relay 134 tok open 'the latter and break the circuit 110- through coil` 63 of the motor..

Contacts 157 and 158 are also providcd,`

as limit switches, to cooperate Withthe rudder in its starboard and portilimiting positions, respectively, to control circuits through 115 coils159 and 160 of relays 92 and 84, respectively, so that as the rudder reaches its limiting positions, the respective relay will be opened to break the circuit through the motor coil 62 or 63. The circuits are as fol- 120 lows; main lead 140, lead 145, contact 157, lead 161, coil 159, to main lead 151; and main lead v140, lead 145, contact 158, lead 162, coil 160 to main lead 151. By energizing Coils 159l and 160, the circuit through the 125i its momentum Would carry it t'o the limits 130 I V157 and 158, which may-be a much greater.

throw than is necessary to counteract the yaw if the latter is small. It isA desirable therefore, to operate the rudder slowly outwardly, `(in the case where there are no intermediate flimit switches) so -that the latter may be moved through any desiredsmall angular distance. For this purpose, when the circuit lthrough the motorv is closed, the 4current passes through coil 201 of relay 200 to open the latter and cause the currentto'pass from The resistance coils n149 and 150 are manuvally settable to adjust the speed of the motor, and hence, of the rudder, tol take care of variationsin sea conditions, load of the ship, etc., which may necessitate slower or more rapid operation of the rudder for equal deviations of the ship.

The motor may be arranged to control a steering mechanism, such as aA telemotor of the usual type. Thus the motor shaft 21() may operate a pinion 211 Which engages two racks 212 and 213 on opposite sides thereof. Said racks operate as plungers in cylinders 214, 215, so that rotation ot pinion 211 will cause one plunger to move inwardly in its cylinder and the other plunger to move out Wardly. This causes aidisplacement of the fluid to one side which is transmitted by pipes ,follow-up mechanism. This followaip mechanism is therefore independent of the steering engine used to operate the rudder, and hence all errors arising in the telemotor, its gearing, transmission, etc. are eliminated so far as the control of the rudder positioning and limiting means are concerned. It the follow-up n'iechanism` which is noW connected to and controlled by the rudder, were connected to the steering engine, all errors arising in the latter would cause errors in the position of the rudder, and hence, in the course of the vessel. By governing the fol- 65 is a series motor, one of the characteristics of which is the picking up in speed thereof the longer it runs, Within a given interval. Thereafter, as the counter-electromotive force builds'up, the speed diminishes. This action of the motor is desirable because for small movements ofthe rudder only the initial comparatively slow speed of the motor is utilized, but Where the rudder is to be operated through greater distances, the motor picks up speed the longer it rotates and thus drives the rudder more rapidly than for small angular distances. It may occur, :however, that the rudder isl operated through so great an angular distance that the motor rotates long enough for the second phase, i. e., the diminishing speed, to setin. To prevent such diminution in speed, there may be provided a relay 225, the coil 2360i which is in series with a resistance 227in the motor circuit. lVhen the circuit is closed, the full current passes through coil 236 so that the relay is held open against the action of spring 228 and the current passes through resistance 227. As the counter E. M. F. builds up, the current in coil 236 is decreased to a point Where it can no longer overcome the tension of spring 228, and the relay is closed. A short circuit is then established through the coil 236, lead 230, contacts of the relay, and lead 231 to cut out resistance 227 and so increase the current, and hence the speed of the motor. So that Where the rudder is to be moved through a large angular distance requiring comparatively long operation of the motor, the speed of the latter will be maintained, or even increased, throughout its operation. The system may be made sensitive hy employing a plurality of relays similar to 225 adapted to be operated successively to cut out an increasing amount of 'resistance and thus provide for acceleraton ofthe motor above, the speed of motor 65 is increased v v This device may be. employedjalso to set the ship ena ditlerent course and maintain it thereon without the manual effort of operating the rudder. For this purpose, the handle 60 is operated to rotate ring 55 in one direction or the other, until the pointer 16 indicates on arbitraryscale 17 the change in heading. Trolley 50 being maintained in a fixed position by the repeater motor, movement of the ring 55 will bring said *trolley into engagement with either contact 51 or 52. Assume that it is desired to turn the ship counter-clockwise. Ring 55 is rotated clockwise through the desired angle so that trolley 50 comes into engagement with contact 51'. The slight yawing movements of the ship will cause engagement between brush 7l and contact 76 to energize the motor to operate the rudder clockwise so as to turn the ship counterclockwise to bring trolley '50.

to the insulating strip 54. As hereinbet'ore described, as soon as the ship starts to turn under influence of the rudder, the latter is brought back to initial position and thereafter the ship will turn under its own momentum. If the ship does not turn the full amount necessary to bring it on the new.

course, trolley 50 will remain in engagement with contact. 51, but nearer'the insulation 5.4.. Upon slight yawing of the ship, brush 71 will again engage contact 76 to throw lthe rudder outwardly in clockwise direction. The ship'again turns counter-clockwise. the rudder is brought'back to initial position, and t-he ship continues to turn under its own momentum. The operation is repeated until trolley 50 reaches insulation 54, i. e., until the ship is on its new course. Thereafter the device operates as hereinbefore described to counteract the effects of yawing and keep the vessel on its new course.

A suitable alarm or indicating device .164 having its own source of energy 165 may be connected in circuit with trolley 50 and contact strip 53, so that an alarm is sounded whenever such unusual turning or yawing of the ship takes place as will cause trolley 5010 engage said strip. This alarm may thus serve to warn against unusual atmospheric or tidal conditions or faults arising from the ship proper.

lt may be found desirable to provide means permitting a rapid, continuous, uninterrupted turning of the ship when a new course is set, or when the ship departs from its course more than a few degrees, insteadl of the step by step movement described in the pre-ceding description. For this purpose, means are provided whereby the rudder returning mechanism, Which is ordinarily effective to return the rudder to central position as soon as the ship starts turning back fromthe position to which it has yawed, is rendered ineffective when a deviation from the'course' greater than that ordinarily vdue yheld outwardly to cause rapid'and continuous turning of the ship, until the latter approaches the desired course, within a predetermined limit. The devlce embodying thls 'principle is shown in the diagrammatic rcpresentation in Fig. 11 in which parts which are the same as in Fig. 10 are similarly humbered. i f

A trolley 50 is in the form of a lever which carries three contacts 168, 169 and 170, the first two upon one arm thereof and the lastupon the other arm. Contacts 168 and 176 engage strips 51,132,171, 172, 173 and 174 of ar contact ring 55', similar to 55. while 'contact 169`engages a. separate contact 176.

' The operation ot' the Adevice is as. follows;

(lace 1.-Assume slight yawing movement in a clockwise direction insufficient: to m'ove contact 168 off insulation 54. A circuit is then established through main lead A140, contact 169, contact 176, lead 141, contact 132, brush 129. relays 134 and 82 to energize relay 84 and coil 68 of the motor to drive the rudder in clockwise direction and move the ship counterclockwise to counteract the yaw. The end of the rudder 66 is provided with or'connected to a block 178 'which closes a set of contacts 17 9.when said rudder moves as described, to close a circuit from main lead 140, lead 180, contacts 179, to energize coil 156 of relay 134 to break the circuit through coil 63 of the motor.- The rudder is held in this position until the ship turns back counterclockwise sutliciently to cause brush 130 to be moved into engagement withcontact 132 to establish a circuit through main lead 140, contact 169, contact 176, lead 141, contact 132, brush 130. relays 143 and 90 to energize relay 92 and coil 62 of the motor to drive the rudder in the opposite direction, i. e., counterclockwise to turn the ship clockwise.A When the rudder engages and closes contacts 181, coil 147 is energized to break thecircuit through coil 62 of the motor. The rudder is held in this position until the ship turns back clockwise sufficiently to bring brush 129 into engagement with contact 132. These small oscillations of the rudder between contacts 179 and 181 are thus continued during the small yawing movements of the. ship to counteract said movements.

Oase Assume greatery deviations of the ship so that contact 168 engages contact 51 or 52, that lcontact 170 does not move out ot" engagement with contact. 174, and that contact 169 does' not move out of engagement with contact 176. If the ship yaws clockwise.

the circuits is as follows: Main lead 140, contacts 168 and 51', lead 79, Contact 76, brush 71 lead 80, relays 82 and 84 to energize coil 63 of the motor to drive the rudder clockwise and thus turn the ship back counterclockwise `to counteract the yaw. For a short distance beyond the insulation 54a circuit will also be established throughv main lead 140, contacts as the ship starts to turn counterclockwise,

brush 71 moves off contact 76 while contact 168 is still on Contact 51, this ,operationv being similar to that in Fig. 10 and the mechanism for effecting it being the same i. e., the slipfriction connection. ot' Fig. 9, which limits the movement ot the commutator 75 relativeyto the brushes 71 and 72. Brush 72 engages Contact 77 but no circuit is established. Brush 130 engages contact 132 to establish a circuit'from main lead 140, contacts 169 and 17 6, lead 141, contact 132, brush 130, relays 143, 90 and 92 to energize coil 62 ot the motor and drive the rudder counterclockwise. The ship continues its count erclockwise movement back'to its course under its own momentum. lVhen the rudder reaches contacts 181, at or slightly beyond its central position in order to effect rapid stopping ot the ships turning, it closes them to energize coil 147 and break the circuit through coil 62 ot the motor.

It the ship yaws in a counterclockwise direction, thelower set of relays energizes coil 62 of the motor to drive the rudder counterclockwise and so turn the ship clockwise hack to its course. When the rudder reaches contact 187 a circuit is closed through main lead 140, contacts 170 and 174', leads 184 and 186, contacts 187, lead 188 to energize coil 89 of relay 90 to break the circuit through coil 62. As soon as the ship starts to turn back clockwise, brush 129 establishes a circuit through the upper set of relays to energize coil 63 of the motor to drive the rudder clockwise. The ship continues to turn clockwise under vits own momentum which carries it back to its course. When the rudder reachesthe centralizing contacts 179, beyond its central position to assist in stopping the ships turning, the coil 156 is energized to break the circuit through coil 63 of the motor.

In Case 2, the device of Fig. 11 operates in part similarly to the device in Fig. 10, i. e., the rudder is thrown outwardly upon yaw v of the ship, in such direction as to move the ship back to its course, and as soon as the shipstarts back, the rudder is returned, leaving the ship to swingback upon its course underitsi'own momentum. In addition. the rudder may be returned slightly beyond its central position to e'ect rapid stopping of the ships turning movement.

Oase .5t-Assume in Case 2 that the deviations are sutiicient to move contact 170 into stead of 183 or 187. lVhcn the rudder moves clockwise, a circuit is .established from main lead 140, through contacts 170 and 173, lead 198, contacts 189, through coil 81 to break the circuit through field coil 63 ot' the motor.

When the rudder moves counterclockwise, the circuit is from main lead 140, contacts 170 and 172, lead 198, lead 191, contacts 190, through coil 89 of relay 9010 break the circuit through coil 62. l l

vOase .tf-Assume that ring 55 is turned to set a new course, or that for some reason. the ship is turned more than 10o (say) off its course, such that contact 169n1oves beyond contact 176 and contact 170 moves beyond contacts 172 and 173, but that contact 168 still engages contacts 51 or 52, It may be assumed that a new course is set because of the improbability ot yaw to this extent taking place. However, whether this deviation is due to yaw or to setting a new course, the operation will be the same; Assume that counterclockwise movement of the ship is necessary to bring it to its new course. A circuit is established through contact 51, brush 71, relays 82 and 84 to coil 63 of the motor. The rudder moves clockwise to cause the ship to move counterclockwise as desired, and when said rudder reaches its limiting position, it closes contacts 193 to energize coil 81 of the relay 82 which breaks the circuit through c oil 63. As the ship starts to turn in the desired direction. however, no circuit is established through the Other-coil o'fthe motor to reverse the direction of the rudder, as in Fig. 10 and in Cases 1, 2 and 3, since contact 169 is oil' contact 176 and there is no circuit through brush 130 to the other coil of the motor, even though said brush is on contact 138 due to the counterclockwise turning of the ship. The rudder therefore holds its extreme positioncausing the ship to'be turned rapidly and continuously, until as the ship nears its course, Contact 169 engages contact 176 to establish a circuit through contact 132, brush 130, relays 143 and 92 to eld coil 62 of the motor 65 to return the rudder to a point slightly beyond .its central position as in the previous cases, to effect a rapid stopping of the ships turning. From this point the momentum of the ship is sufficient to carry it substantially to its course, which it approaches slowly as heretofore described, when contact 50` will engage insulation 54.

The circuits when the ship is to be turned clockwise, will be readily ap arent, and will lie through'contact 52, brush 2 and the lower set of relays to coil 620i the motor to move the rudder counterclockwise and move the ship clockwise. In its extreme position the rudder causes contacts 194 to engage and energize coil 89 of`relay 9() to break the circuit hrough coil 62. The rudder is held in eX- treme position until the ship turns so that contact 169 engages contact 176 to establish a circuit through contact 132, brush 129, re-

lays 134, 82 and 84 to coil 63 of the motor.

The rudder is operated clockwise and is rcturned to centralized position where it is hcld by closing contacts 179 to energize coil 156 of relay 134 to break the circuit through coil 63 of the mot-or.

It is thus apparent that when the ship is to be moved throughlarge angular distances either to return it to its course after an eX- ceptionally large yawing movement, or when a new course is set involving a large deviation from the previous course, the rudder is thrown outwardly and held in its extreme position until the vessel has moved through the greater part of the required angular'dlstance in the desired direction. lAs the vessel nears its course, the rudder is swung back to substantially centralized position and the angular movement ofthe ship damped out by the time it reach-es its course. By this means a rapid change of course may be accomplished for large angular distances,finstead`of the retarded movement disclosed inFig. 10.

It will also be apparent from the description of the device in Fig. 11 that a plurality i of intermediate limiting positions for the rudder are provided by the contacts 183, 187, 189 and 190, in addition to the centralized and extreme limit positions of Fig. 10. The plurality of limiting positions correspond to the varying degrees of yaw or varying degrees of change in course, so that thethrow of the rudder is in proportion to the amount of deviation. Thus, for a change in course insufficient to cause contact 17 O to leave contact 174, the rudder will move until it closes contacts 183 or 187; for a change in course sufficient to cause contact 170 to engage contacts 172 or 173, the rudder will move until it engages contacts 189 or 190.

Between motor 65 and the rudder, there may be interposed a similartype of steering telemotor as in the device of`Fig. 10. Here, also, the follow-up mechanism for controlling the circuit in accordance with the positions of the rudder, is connected to and leads from the rudder proper. No errors existing in the transmission system ofthe telemotor can possibly be transmitted to the rudder to give an incorrect position to the latter, as would be the case if the follow-up mechanism were operated by the steering engine rather than directly from the rudder.

Similar to the Fig. 10 ldevice there may be interposed in the motor circuit, one or a plurality `of relays 225 to cause the motor, to

accelerate the greater the angular distance through which the rudder is operated, and the longer the period of operation of the motor. Thus, as the rudder is mov-ed to engage only contacts 179, the initial speed of the motor is sufficient, but where the rudder is driven to engage contacts 193, it may be found that the motor has diminished in speed before the rudder has reached its limiting position. By the use of these relays, as described in connection with Fig. 10, more resistance is cut out of the circuit the longer 'the moto;` rotates, and

thus increases or sustains the' speed of the The device shown in Fig. 11 may be proi vided with the alarm 164, as in Fig. 10, in circuit with trolley 50 and contacts 171 Vthrough leads 195 and 140, said alarm functioning as described Ain connection with the device in Fig. 10.

If a record is kept ofthe movements of a rudder operated by myyautomatic steering mechanism, it will appear as in Fig. 12 which is a portion of an actual record. The course or ainidships position ofthe rudder is indicated by the line in the left hand graph. It will be observed that most ofthe deviations are` b tween the lines Y, corresponding to the dista cebetween contacts 179 and 181.' 0ccasionally, there is a deviation to lines Z, corresponding to contacts183 and 187. Ordinary yawing movements exceed these angular distances. However, yaw may take place between contacts l189 and 190, which would 4be indicated by lines W, or between contacts 193 and 194 indicated by lines V. These records will, of course, be made also when the rudder is thrown outwardly for a change of course.

The right hand graph in Fig. 12, indicates` the course of the ship, and it is evident that the movements of the rudder are in exactly opposite direction and indicates an almost instantaneous response of the rudder to changes in the ships course. The graph of thel rudder movements is full scale, but the graph'of the ships deviations is magnified considerably, so that actually the deviations of the ship from its course are inappreciable.

In accordance with the provisions of the patent statutes, I have herein describedthe 'principle of operation of my invention, to-

gether with the apparatus, which I `now consider to represent the best' embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and. that theinvention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, so'me of these may bel altered and others omitted without interfering with the more .general results outlined, and the invention extends to such use.

Having herein described my invention, what I claim and desire to secure by Letters Patent is,

1. In an automatic steering mechanism, means responsive'to the movement of a vessel off its course for opposing said movement and tending to return the vessel toits course, and means for rendering said first named means ineffective when said vessel starts on its return movement.

2.' In an automatic steering mechanism, means responsive to the movement of a vessel offl its course for opposing said movement and operating to return the vessel to its course, and means actuated on the initial return movement of said vessel for rendering said first named means ineffective before said vessel reaches its course.

3.v In an automatic steering mechanism, means responsive to the movement of a vessel off its course for counteracting said movement and imparting a return momentum to said vessel, and means for rendering said first named means ineffective before said vessel reaches its course.

4. In an automatic steering mechanism, a controller responsive to the deviation of a vessel off its course for counteracting said movement and returning said vessel to its course, a second controller responslve to l change in the direction of yaw, a steering en- 'ne, and means including interlocking reas between said controllers and engine w ereby the tendency of the rvessel to overrun its course when being returned to its course after deviation is counteracted. l

5. In an automatic steering mechanism for a vessel having a rudder, a controller responsive to the movement of the vessel off its course for operating the rudder in a direction to' counteract said movement and return the vessel to its course, said rudder being normally positioned to maintain the vessel on its course, a second controller responsive to change in the direction of aw of the ship, a steering engine, and inter ocking relays between said controllers and engine whereby the rudder is returned to its normal position before the vessel swings back to its original course.

6. In an automatic steering mechanism for dirigible craft, means for setting a new course for the-craft, means rendered effective by said first named means'for operating said craft toward thev new course, and means whereby said last named means is rendered ineffective before said craft reaches said new course.'

7. In an automatic steering mechanism for dirigible craft, means for setting a new course for the craft, and means rendered effective by said first named means for imparting a plurality of successively diminishing impulses to said craft for bringing it ytoward the new course.

.8. In an automatic steering mechanism for dirigible craft, said craft having a rudder normally in centralized position whcnsaid craft is traveling on it-sl course, means responsive tothe vmovement of the craft off its course for operating the rudder in a direction to counteract said movement and return the craft to its course, means for returning said rudder before the craft reaches its course, and means whereby said last named means is rendered ineffective when the rudder reaches its substantially centralized posi-h means responsive to the movement of a vessell off its course for` counteracting said movement, said means comprising means for imparting a plurality'of successively diminishing impulses to said vessel; all of said impulses being in the same direction for restoring it to its course.

11. In an automatic steering mechanism, means responsive to the movement of a vessel off its course for counteracting said movement, said means comprising means for/imparting a plurality of successively diminishing impulses to said vessel, all of said impulses being in the same direction for restoring it to its course and means whereb sa'd last named 4means is rendered ine ectilve when said vessel reaches its course.

12. In an automatic steering mechanism for dirigible craft, means for setting a new course for the craft, means rendered effective by said first named means for imparting a plurality of successively diminishing impulses to said craft for bringing it toward the new course and means whereby said last named means is rendered ineffective when said craft reaches the new course.

13. In an automatic steerin for dirigible craft having a ru der, a course mechanism y loov control device responsive to turning of the craft, a reversible engine for controlling the rudder of the craft, an auxiliary control device responsi-ve to changes in the direction of turning of the craft, means interconnecting said devices and engine whereby the position of said rudder depends on both the heading and theangularmovement of the ship at the time, said engine being inoperative when said craft is on its course, means whereby saidvll devices operate when said craft moves offy its course, to drive said engine and operate the rudder in a direction for returning the craft to its course, means whereby said auxiliary device responds to the return movement of the craft to reverse the direction of operation of said engine before the craft reachesits course, and means operated by said rudder in substantially centralized position for rendering said last named means ineffective. Y

.145111 an automatic steering mechanism for dirigible craft having a rudder, a course contiol device responsive to turning of the craft, ai'eversible engine for controlling the rudder of the craft, an auxiliary control device responsive toI changes in the direction of turning of the craft, meansinterconnecting said devices and engine whereby the position of said rudder depends on both the heading and the angular movement of .the ship at the time, said engine being inoperative when said craft is on its course, means whereby said devices operate when said craft movesoff its course to drive said engine and operate'the rudder in a direction for returning the craft to its course and means operated by said rudder in its limiting positions to render said last named means ineffective. s

15. In an automatic steering mechanism for dirigible craft having a rudder, a course control device responsive to turning oflthe craft, a reversible engine for controlling the rudder .of the craft, an auxiliary control device responsive to changes in the direction of turning of the craft, means .interconnecting said devices and engine whereby the position ofsaid rudder' depends on both-the heading and the angular movement of the ship at the time, said engine beinginoperative when said craft is on its course, means whereby saiddevices operate when said craft moves off itsy course, to drive said engine and operate the rudder in a direction for returning the craft to its coui'se, means operated by said rudder in its limiting positions to render said last named means ineffective, meanswh'ereby said auxiliary device-responds to the return movelment of the craft to reverse the direction of operation of said engine before the craft reaches its course, .and means operated by said rudder in substantially centralized position for rendering said last named meansv ineffective. I, y.

16. In an automatic steering mechanism fsaid devices and engine whereby the position of said rudder depends on both-the hea-ding and the angular movement of the ship at the time, said engine-being inoperativev when said craft is on its course, means whereby said devices operate when said craft moves oif its course, to drive sai`d engine and operate the rudder in a direction for returning the` craft to its course, Imeans whereby said auxiliary device responds to the return movement ofthe craft to reverse the direction of operation of said engine before thecraft reaches its course, means operated by said rudder in substantially centralized position for rendering said last named' means ineffective and means whereby said devices operate said engine a plurality of times in a direction to return the craft to its course;

17. In an automatic steering mechanism for dirigible craft having a rudder, a course control device responsive' to turning of the craft, a reversible engine for .controlling the rudder of the craft, an auxiliary control device responsive to changes in the direction of turning of the craft, means .interconnecting said devices and engines whereby .the position of said rudderdepends on both the heading and the angular movement of the ship at the time, said bourse-control device being operable to set a new course, means whereby said devices operate to drive said engines to operate the rudder in al direction Ufor moving the craft to its new course, means whereby said auxiliary device operates to restore said rudder to initial position when-said craftmoves toward the desired course and means whereby said deviees operate said rudder repeatedly to drive the craft in the desired direction until the craft reaches its new course.

18. In an automatic steering mechanism for dirigible craft, a @purse control device responsive to the movements of a gyro compass, a reversible motor for controlling the rudder of the craft, an auxiliary device also responsive to the movements of said compass and interposed between said control dcvice'and the motor, said motor being inoperment of t-he craft when the cra-ft is being returned through a. rela-tively large angular distance. 4

20. In an automatic steering mechanism for dirigible craft, means responsive to the movements of the craft off its course for counteracting said movement and returning the craft to its course, means for retarding ang'ular return movement of the craft, and means whereby said last named means is rendered inoperative for a portion of the return movement of the craft when the craft, is to be returned through a relatively large angular distance and again rendered operative as the craft approaches its course.

l21. In an automatic steering mechanism for dirigible'craft, means for setting a new course for the craft, means rendered effective by said first-named means for operating said craft toward the new course, means for retarding angular movement of the craft to-- ward said new course, and means whereby sald last named means is rendered inoperative for a portion of the returnmovement of the craft when said craft is being returned through a relatively large angular distance. 22. In 'an automatic steering mechanism for dirigible craft, means for setting a new course for the-craft, means rendered effective by said first-named means for operating said craft toward the new course, means for retarding angular movement of the craft toward said new course, and means whereby said last named means is rendered inoperative for a portion of the return movement ofthe craft when said craft is to be turned through a relatively large angular distance and is again rendered'operative as the craft approaches the new course;

' 23.4 In an automatic steering mechanism for dirigible craft havin a'rudder, a-master oo ntroller responsive to the movements of the craft o its course for operating said rudder in a direction for. counteracting said movements and returning'the vessel to its course, and means independent of said controller and operated by said rudder for stopping said rudder when saidgrudder is operated through an angular distance pro ortional to the movements of the craft o its course. 'y

24. In an automatic steering mechanism fr dirigiblel craft having a rudder, means for setting a newl course for the craft, means actuated by said first named means for oper- .erating member in said slot ating the rudder in a direction to :move the craft to its new course, means whereby said "rudder is moved th ough an angular distance proportional to the ngular distance through which the craftis to be turned, and means for vreturning the rudder, when the craft approaches its new course, to a point slightly beyond its central position.

25.V In an automatic steering mechanism adapted to be controlled by a gyro compass subject to hunting, a master controller operatively connected to said compass, and means for preventing transmission of the hunt of `said compass to said controller, said means comprising a two-part connection between said compass and said controller, one of said parts having an operating member, and the other of said parts having a tapered slot in which said operating member operates loosely to effect lost-motion, and means for adjusting the position of said opto vary the amount of lost-motion. Y

26. In an automatic steering mechanism adapted to be cont-rolled by a gyro compass subject to huntingf a master controller op-.

loperated by said compass, a member in said casing and operated by said motor, and mean? for preventing transmission of the"hunt of said motor to ,aid member, said means comprising an operating member operated by said motor, said. member having a vertically positioned wedge-shaped openlng in whic vsaid operating member operates loosely to effect lost motion, and means positioned outside of said casing whereby the position of be adjusted to vary the amount of lost motion.

28. In 'ail automatic steering mechanismV adapted to be controlled by a gyro compass, a casing, a repeatermotor in said casing and operatedlby said compass, a member in said casing and operated by said motor, and means for preventing transmission of the hunt of said mot-or tosaid member, said means comprisingan operating member operated by said motor, said member having a verticallypositionedwedge-shaped openlng 1n wluch said operating member operates loosely 'to effect lost-motion, a cam member engagmg said operating member, and means positioned said operating member in said openmg may outside of said casing for operating said cam member to adjust the position of said operating member in said opening to vary the amount of lost motion. i

29. In an automatic steering mechanism for dirigible craft having a rudder, 4a course control deviceresponsive to turning of the craft, an auxiliary control device responsive to turning of the craft, a reversible engine for controlling the rudder, means controlled by said rudder, andv interlocking relays for controlling said engine, said devices and 'said rudder controlled means controlling said re lays.

30. In an automatic steering mechanism for dirigible craft having a rudder, a reversible steering engine for controlling the rudder, a plurality of relaysfor controlling said engine, means responsive to the turning of the craft off its course for actuating certain of .off its course for actuating one of said sets of relays to operate the motor and drive the rudder in a direction to bring the craft back on its course, means actuated by the rudder for rendering said last named set of relays ineffective, and means responsive to a change in the direct-ion of turning of the craft for actuating a second set of relays to operate the motor and drive the rudder in a reverse direction.

32. In auautomat-ic steering mechanism 'for dirigible craft having a rudder, a reversible motor for controlling the rudder, a plurality of relays for controlling said motor, means responsive to the turning of the craft ofi' its course for actuating one of said relaysto operate the motor and drive the rudl der in a` direction to bring the craft back on its course, means actuated bythe rudder` for rendering said last named relay ineffective, means responsive to the directionl of turning of the craft for actuatino' a second relay to operate the motor and drive ,the rudder in a reverse direction, and means actuated bythe rudder for rendering the second relay ineffective.

33. In an automatic steering mechanism for dirigible craft having a rudder, means responsive to the movement of .the craft off its course for operating the rudder in a di-v turn the craft to its course and means for returning the rudder to initial position at a greater speed. than'said rudder was operated outwardly.

34. In an automatic steering mechanism for dirigible craftA having a rudder, means responsive to the movement of the craft off its course for operating the rudder in a direction to counteract said movement and return the craft to its course and means actuated on the return movement of the craft `for returning the rudder to initial position at a greater' speed than said rudder `was operated outwardly.

35. In an automatic steering mechanism for dirigible craft having a rudder, means responsive to the movement of the craft of..

its course for operating the rudder in a direction to counteract said movement andreturn the craft to its course,` means for returning the rudder to initial position, and means whereby the outward movement of the rudder and the return movement thereof are performed at different speeds.

36. In an automatic steering mechanism for dirigible craft having a rudder, means responsive to the movement of the craft off its course for operating the rudder in a direction to counteract said movement and return the craft to its course, means for returning the rudder to initial position, and means whereby therudder is moved outwardly at a speed relatively slow compared with the speed of the return movement thereof.

37. In an automatic steering mechanismy for dirigible craft having a. rudder, an electrical course controller', means actuated by said cont-roller for turning said rudder, said means including an electric motor adjacent said controller and actuated thereby, a telemotor system actuated by said motor, a steering engine controlled by the telemotor for turning the-rudder, and a second electrical controller actuated bythe movements ofthe rudder providing a follow-back system independent of said telemotor.

38. In an automatic steering mechanism course for operating the rudder in a direction.

CHESTER B. MILLS. 

